Methods for reducing aldehyde emissions in polyurethane foams

Abstract

Polyurethane foams are made by curing a reaction mixture that contains an aromatic polyisocyanate, at least one isocyanate-reactive material having an average functionality of at least 2 and an equivalent weight of at least 200 per isocyanate-reactive group, at least one blowing agent, at least one surfactant and at least one catalyst, at least one cyclic 1,3-diketone and at least one aminoalcohol or alkylhydroxylamine. Foams so produced emit low levels of formaldehyde, acetaldehyde and propionaldehyde.

What is claimed is: 
     
       1. A method for producing a polyurethane foam comprising forming a reaction mixture that contains an aromatic polyisocyanate, at least one isocyanate-reactive material having an average functionality of at least 2 and an equivalent weight of at least 200 per isocyanate-reactive group, at least one blowing agent, at least one surfactant and at least one catalyst, and curing the reaction mixture in the presence of (i) 1,3-cyclohexanedione, (ii) 0.05 to 0.25 parts by weight, per 100 parts by weight of the at least one isocyanate reactive compound having at least two isocyanate-reactive groups per molecule and an equivalent weight of at least 200 per isocyanate-reactive group, of 1,1,1 tris(hydroxymethyl) methylamine and (iii) a phenolic antioxidant, to form the polyurethane foam. 
     
     
       2. A method for reducing aldehyde emissions from a polyurethane foam, comprising: a) combining (i) 1,3-cyclohexanedione, (ii) 1,1,1-tris (hydroxymethyl) methylamine, and (iii) a phenolic antioxidant, with at least one isocyanate-reactive material having an average functionality of at least 2 and an equivalent weight of at least 200 per isocyanate-reactive group to provide 0.05 to 0.25 parts by weight of the 1,1,1-tris (hydroxymethyl) methylamine per 100 parts by weight of the at least one isocyanate reactive compound having at least two isocyanate-reactive groups per molecule and an equivalent weight of at least 200 per isocyanate-reactive group, and then b) combining the mixture from step a) with at least one organic polyisocyanate and curing the resulting reaction mixture in the presence of at least one blowing agent, at least one surfactant and at least one catalyst to form a polyurethane foam. 
     
     
       3. The method of  claim 1  wherein the cyclic 1,3-cyclohexanedione is present in an amount of from 0.03 to 0.25 parts by weight per 100 parts by weight of the at least one isocyanate reactive compound having at least two isocyanate-reactive groups per molecule and an equivalent weight of at least 200 per isocyanate-reactive group. 
     
     
       4. The method of  claim 1  wherein the phenolic antioxidant is present in an amount of 0.2 to 1.5 parts by weight per 100 parts by weight of the at least one isocyanate reactive compound having at least two isocyanate-reactive groups per molecule and an equivalent weight of at least 200 per isocyanate-reactive group.